A character duck often wants three colors: body, bill, eyes. Multicolor printing can do that in one job. It can also spend more plastic on purge than on the duck. Choose it on purpose.
When one nozzle and a paintbrush win
If you sell or collect a few ducks, paint is predictable. Print the body, paint the bill and the eyes, and skip purge towers. The capsule eye is small. A careful brush is sometimes cleaner than a color change that leaves a speck in the socket.
When the machine should change color
Use filament changes or a multi-tool printer when you want repeats that match, or when a color boundary is a hard edge in the model. A yellow body with a separate orange bill is a good candidate. A tiny printed logo in a fifth color often is not.
Waste is part of the price
Every color change can purge a blob. Count those grams. They belong in the price if you sell the duck, and they belong in your spool budget if you do not. A palette with four colors is usually enough. See color choices.
Keep the face stable
Color changes add time. A small eye can sag or pick up strings while the toolhead is away purging. Slow the layers that form the eyes, and watch the first one. If the eye closes up, fix that before you add another accent color.
Prime and wipe the way your printer’s manual describes. A smear of black across a yellow cheek is the defect people see in the photo.
File rules do not change
Splitting a mesh so you can print colors does not give you a new file you may upload. The commercial license still treats derivative digital files as Duck Heroes property when the source is a Duck Heroes model. Paint on a physical duck is fine. Publishing the recolored STL is not.
The catalog is not open yet, so there is no official multicolor project file on this site. When models arrive, use the supplied split if there is one. Do not assume every theme was built for a particular multicolor system.